Generally, a wind turbine includes a tower, a nacelle mounted on the tower, and a rotor coupled to the nacelle. The rotor generally includes a rotatable hub and a plurality of rotor blades coupled to and extending outwardly from the hub. Each rotor blade may be spaced about the hub so as to facilitate rotating the rotor to enable kinetic energy to be converted into usable mechanical energy, which may then be transmitted to an electric generator disposed within the nacelle for the production of electrical energy. Typically, a gearbox is used to drive the electric generator in response to rotation of the rotor. For instance, the gearbox may be configured to convert a low speed, high torque input provided by the rotor to a high speed, low torque output that may drive the electric generator.
The gearbox generally includes a gearbox housing containing a plurality of gears (e.g., planetary, ring and/or sun gears) connected via one or more planetary carriers and bearings for converting the low speed, high torque input of the rotor shaft to a high speed, low torque output for the generator. In addition, each of the gears rotates about a pin shaft arranged within the one or more planetary carriers. The gearbox is then attached to the bedplate via a torque arm. More specifically, for conventional wind turbines, the ring gear of the gearbox is a separate component from the torque arm and is thus fastened to the torque arm via one or more fasteners and/or flanges.
Thus, the ring gear and the torque arm are separately manufactured from different materials to accommodate varying stresses and/or loading. More specifically, the ring gear is generally formed via forging, whereas the torque arm is generally formed via casting. As such, the manufacturing process for the ring gear and the torque arm requires at least two completely separate manufacturing processes with the resulting parts being joined together via connecting fasteners and flanges. The ring gear must also be subsequently heat treated to obtain a certain hardness. Thus, the aforementioned manufacturing techniques are complex and expensive. In addition, the heat treatment may cause dimensional distortion.
Accordingly, an improved gearbox assembly for a wind turbine and method of manufacturing same that addresses the aforementioned issues would be welcomed in the art.